Which of the following macromolecules de /k n y4: fyyt-x:v1xq vp2v9o7myv1hpscribe a typical enzyme?

  What type of reaction is photosynff(-k mz; lx2/co;n eothesis?

  What is the substrate for thej3evtt2gw 9ut/0f t0g enzyme lactase?

  Which of the following stages of cellular resh.1iqrj1yqb,gg2 meq h 4 5wvn/y3;i xpiration takes place in the cytoplasm?q32.y y/g ,1hiewxr1vq j;g nmqihb4 5

  Which of the following would not be useful in determining the rate ofj . e )59p oznqomgvt(sp-/om2 an enzyme-catalyzed re5on/ .)gjoovz( 2 m9tm-qs ppeaction?

  Which of the following processes may be described as catabolism?j 6kb6 +dgov5e4 wv2umtvx2+ h

  Which of the following statements is best depictedos0qlmzv pof9p/l2,ued:z 9 1 by the figure below?

  Which statement about enzymes is noa)czx+pbjod3- u).w,jsux: y t true?

  Which of the following graphs best illustrates the relatio d-fpta;7c*jznship between temperature and the activ-z7da; jftpc* ity of enzymes such as lipase?

1.Sketch a graph to show how increasing concentrations og ;l+ wun(xtl2f substrate affect enzyme activity. ( tx;lu+n l2gw
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a sem2fdngf 25. 2dyn;d pbries of enzyme catalysed reactions. A diagram outlining the Calvin cm2n 2f 2pg. fdyd5bnd;ycle is shown below.

The image below shows the catalytic site of an enzyme. The +5gpm ya v tfm2:ksn/m+o0,gpiz9v.usubstrate is shown in black and is bound to po9 /yua ,sgfk.v 20gmt+mn+mpvi5:zthe active site.





1.State how the activation energy is changed by adding an enzyme to a reaction.
2.Distinguish between anabolic and catabolic pathways.

  Which are correct descriptions ow.skfw ,g21hlfgx0d8f the enzyme catalysed metabolic pathways shown below? f2dxkhf ,.1glsg0w 8 wLetters represent various products of individual reactions.

  Which of the following descae 0q-1hp4* 41g, zmfvnzzp/2q jtjepribes the role of inhibitors in enzyme-catalysed reactions?-0zjh pjtg*e2,n/ev14qpmq fp 4zza 1

  Which of the following correctly describes photosynthesi7djh h7 f lxf+6ci;+wes or respiration?

Many enzymatic reactions happen as pathways involving multiple steps and mu1rl n j5exmp51ltiple enzy 5mnepx 1r1j5lmes.

1.Describe how enzymes catalyze reactions.
2.Outline the advantages of enzyme-substrate specificity.

  Which of the following best describeya9nh zoa: 3qz:-s (qqs the inhibitor in the image below?

  Which of the following stateik4* 0 l z8nt-j/pucdaments are true regarding regulation by end-product inht 4 k0il/*8jzu ndap-cibition?
I. The end product binds to the allosteric site of the enzyme.
II. The binding of the end product is reversible.
III.End product inhibition is an example of negative feedback regulation.

  The following image shows the structure of the lysozan;;vlor +i h(;kkwt1c;6q ogyme enzyme. The darkened structure in black is the substrate and is bound at thcgn6h; v; kqrtwki a(oo+l;;1e active site.

Which of the following characterizes the active site of an enzyme?

The equipment below can be us kwe +t 8ft1n3xe m5z2+n+yctked to study the effect of temperature on the activity of the ene21tte +kt+3n 5wk8zy xcf+m nzyme amylase.



1.Outline how this equipment could be used to set up a study into the effect of temperature on amylase activity, up to the point of getting the results.
2.Outline how the rate of reaction of the breakdown of starch by amylase could be measured using the equipment given.
3.Describe a suitable control experiment for this study.
4.Suggest one way to increase the reliability of the data that can be gathered from this experiment.
5.Using the axis below draw a graph of the expected results from the study in part (a).

  Which of the following statements describes how enzymes interact with substrab:tv0:xc i r*igvo9m;tes to catali mr9v : c;*xvbg:i0toyze reactions?
I. Enzymes and substrates in solutions collide with one another, and the substrate is bound at the active site.
II. There is more movement of the substrate in a reaction because the substrate is usually smaller than the enzyme in size.
III.When the substrate binds to the active site, the shape of the enzyme changes slightly so it can accommodate the substrate.

Outline two ways enzyme catalysed reactions can be m*a4i/of*b azdeasured.

  How does denaturation change the pr mg6 c(s (doi68/nrfu:p m:druoperties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following statement x;18h1a( 6fchmunld ciz2 ;vds are tdx(dniz;u1m 6 fchcl;v1ha28rue?
I.The substrate is temporarily provided with energy before being converted to a product.
II. Enzymes reduce the activation energy needed for the reaction.
III.The active site binds to the substrate making it easier for bonds to be broken or formed.

  What is a characteristic that separates mammals or endotherms from7vdcop-0+p7+qpjgc-.0edy; ik i ot o trs(b7 ectotherms that have fluctuating body tempe+cdv i; 0rd qstoegb.ippcok 7-7-y+ 0o7pjt( ratures?

  A metabolic pathway that converts threonine to the end94rdboq 6+j8 8k2 n6a;pkw4vu,jlum zym2 h cd-product isoleucine consists of five reactions. 62+ mdwl jbza9r,pn8;4 o8v6mk2qcy d j hu4ukThreonine is converted to various intermediate products sequentially by different enzymes before it is converted to isoleucine by the last enzyme in the pathway.
In the following diagram, the enzymes have been labelled as E1, E2, E3, E4 and E5.


Which of the following shows how this pathway is regulated?

  The graph shows the effect of increasing pHr1jg*7klds w) q x55/:mgbkeatr.i2 p on the rate of an enzymatic reaction. What is occurring during the phasesbd2l1i /ap 7er5: xkqtmkg*j 5wgr .) labelled section X in the graph?

  An experiment tests the 0872o f qnbga clb)4j/rovq(ipdu y96effect of changing substrate concentration on an enzymatic reaction. What could be the independent and dependent varo c/upv)l f9gb( 6idaoyj b4q2nr8 q70iables in this experiment?

  The diagram shows the pathway that converts threonine to ie;i 3uurg10crnph3 9 k op,e:bsoleucine.



What is the name and mechanism of the process through which isoleucine interacts with threonine dehydratase?

  Enzyme A (Enz A) was immobilize.uqs+*,ib fx3 h1xxjlcf 1rr.d on a matrix and its activity was compared with that of a free enzyme in solution. *jrx+xh u3cf. frx,sbql 1i. 1The graph shows the relative enzyme activity (y-axis) with varying pH (x-axis).



Which of the following statements is true?
I. Both soluble and immobilized enzymes are inactive at higher pH values of 8.
II. The immobilized Enz A is more resistant to pH changes showing more activity than the soluble enzyme at most tested pH values.
III. Immobilizing Enz A did not decrease its catalytic activity.

  Purified enzymes are easily denatured. Which of the following is the best way to4:ph83ft0zvl g wq1 cz n8a5hw keep enzymes active for a longer period of ti8f z80hgplz5q 1v:wwha c43nt me?

  Which of the following describes souw 0lx-o phr69 uy95tg8fxe r5me types of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides in the stomaktac-nn vre./(q u+c,ch. A study was carried out to determine t v nnce.uckat,/+r(q- he effect of increasing substrate concentration on enzyme activity at a constant temperature of $30{\circ}C.

1.Describe the trends shown by the graph.
2. 1.Outline why it is important that temperature is kept constant in this experiment.
2.State one factor other than temperature that would need to be controlled in this experiment.
3.Suggest a method that can be used to maintain a constant temperature in this experiment.
3.Calculate the rate of reaction during the first 4 minutes when the enzyme pepsin is exposed to 5 mM of protein. Make sure you show your working. ----待选择----+-   
4.Explain the observed results.

  The graph below shows the rate of reactio(saegb,m+ 9rbiiz h ./n of an enzyme with increasing substrate concentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activbg +9bm e .zsi/(rahi,ity was monitored for each of the reactions. The curve marked A coincides with the activity of the enzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a student cut a turnip roopn7b j5d pr4vl r/7ufvdeo/9 8t into small cubes. They measured approximately 5 g in a wei8/o94l7e 5b njd7dpprurvv /fghing dish, added 50 ml water and used a blender to homogenize the turnip root. The homogenate was filtered and the liquid extract was stored in a test tube at room temperature.


The turnip extract and water were added to the conical flask first. Then 3% hydrogen peroxide solution was added to the conical flask, as shown in the image above. The oxygen produced is collected over 1 minute and measured in an inverted measuring cylinder, as shown.
The student wanted to conduct an experiment to see the effect of increasing enzyme concentration on the reaction. She made up the different concentrations as shown in the table below and added 1 ml of 3% hydrogen peroxide to each.

1.Suggest why the process of grinding the turnip root and extracting the filtrate was carried out.
2.State the dependent variable.
3.Explain why the volume of water was varied, as shown.
The following graph was obtained when the student varied the substrate (hydrogen peroxide) concentration, keeping the enzyme concentration constant.



4.From the graph shown above, calculate the percentage increase in volume of oxygen gas produced when using 1% hydrogen peroxide compared to 0.5% hydrogen peroxide.  %
5.Outline the reasons for the shape of the curve obtained.
The student repeated the same experiment but added an inhibitor along with the enzyme to the reaction mix. She got the following results.


6.Deduce, with an explanation, whether a competitive or non-competitive inhibitor was used in the investigation.
7.Other than the factors already mentioned, state one other factor that can lower the rate of an enzyme controlled reaction.

  The mevalonate pathway is shown below. Inhibitors to the enzyme HMG- CoA re tq qw1/3:9pbafn2ogve8 zs m57qn9arductase can los qn9p5frw2z7q9 qmb/t o vn3e 1:aga8wer the production of cholesterol.


Statins lower cholesterol, reduce the risk of heart attacks, and prevent strokes. They are known to inhibit HMG-CoA reductase, which is the rate-limiting enzyme of cholesterol biosynthesis in the mevalonate pathway (image above).
Which of the following describes the mechanism of action of statins in lowering cholesterol?

  Which of the following are invol./o tyjmg u9wo4 zdr06ved in denaturation?
I.A change to the three dimensional structure of the protein
II. A change in the amino acid sequence of the protein
III. Changes in the properties of the protein

  Students were investigati)j*5f1y2 dpcyyp,jl as 1k7bkng metabolic reactions in the classroom and were given an experiment which 51yfkkjp pc,)7 *j lsbd2 1ayydemonstrated the effect of temperature on a catabolic reaction.
A sample of fat was added to a beaker, which contained 150ml of a 1% sodium chloride solution.


The beaker and its contents were then added to a water bath, which was set at 15
o
C. The beaker was given 5 minutes to equalise with the temperature of the water bath. After 5 minutes, 5 ml of a 2 % lipase solution, at the same temperature as the water bath, was added to the beaker.


5 ml of 2 % sodium hydroxide (NaOH), pH 8.4, was added to a test tube and phenolphthalein, a colourless solution which turns pink in basic environments, was then added. The intensity of the pink colour is proportionate to the strength of the basic solution.
At exactly 20 minutes, a 5ml sample was taken from the beaker incubated in the water bath and added to the test tube.

The contents of the test tube were then immediately transferred into a cuvette and placed in a spectrophotometer set at 420 nm. The percentage transmission of light able to pass through the sample was measured and recorded.

The procedure was then repeated using water baths set at a range of different temperatures. The measurements were recorded in a table and presented in a graph.



1. 1.State the independent variable in this experiment.
2.Identify two factors, not already mentioned, that would need to be controlled in this experiment
2. 1.Explain how the spectrophotometer is able to measure the breakdown of fat.
2.Explain the effect of increasing the temperature from 15
o
C to 35
o
C on the rate of the catabolic reaction.
3.Predict the percentage transmission for a sample incubated at 20
o
C.  %
4.Evaluate the claim that based on the data, the optimum temperature for lipase activity is 35
o
C.

  In an experiment, the effect of increasing temperature on the efficiency of lfes,.m- l8rz. b5; -(onhx g9lo jjocuactase activity 8jxuf5b-jc z nl.lhesg o.or-9 , ;(mois tested. Which is an appropriate dependent variable for this experiment?

  A study has been conducted on dc*9 ug;1s,hpbq4a ri the activity of a specific lactase (Bg10), analysing the effect of pH, temperdb ha9gu4 pr*,; sq1icature and glucose concentration, as it may potentially be used as a commercial lactase to produce lactose-free milk.



1.Deduce which temperature used in this experiment was the optimum one for the enzyme Bg10. Give a reason for your answer.
2.Explain the change in enzyme activity at temperatures above $40^{\circ}C$.
3.Evaluate whether the data supports the claim that the optimum pH for the lactase enzyme Bg10 is 7.

4.Calculate the percentage difference in relative activity of the enzyme Bg10 when treated with 500 mM of glucose compared to 50 mM of glucose. Make sure you show your working.  %

Further studies have been conducted on other lactase enzymes to test their thermal stability at an optimum temperature of 60°C, when they are immobilised on graphene nanosheets, in comparison to lactase enzymes floating freely in milk.

5.Compare the trend shown by the immobilised enzyme to that of the soluble enzyme.
6.Calculate the range of data for the soluble enzyme over 10 minutes.  log %

The storage stability at room temperature of the immobilised enzymes has also been compared to lactase enzymes floating freely in milk.


7.Compare and contrast the storage stability of the immobilised and free soluble enzyme.

The reusability of the immobilised enzyme was tested, by analysing the activity of the immobilised enzyme over 10 uses.


8.State one advantage of being able to reuse immobilised enzymes.
9.Using the data provided, and your own knowledge, suggest why immobilised enzymes should be used to make lactose free milk.

1.There is a continuous need to find new drugs for treating patixxq qv9 1hh.og.h l-ixph7o+q x8i:9h ents with malaria. Desop9gxi81. h-h97hhv ol h :x. +qxiqqxcribe how anti-malarial drugs are being discovered with new technologies.
2.Enzymes are regulated by inhibitors that are classified as competitive or non-competitive. Distinguish between these two types of inhibitors.
3.Describe, using an example, how metabolic pathways can be regulated by end-product inhibition.

1.Explain how increasing td8gjb k: cxb89:yjpg ,he concentration of an enzyme affects the rate of reactij9 kx: 8g,gy:bc8jpd bon.
2.Lactase converts lactose to glucose and galactose. Outline how lactase is used in the food industry.
3.Discuss the industrial use of immobilized enzymes using a named example.

  Biomolecules can be brag*g3v*qo. hr:kkfg7 oken down or synthesized through metabolic reactions. Which type(s) of metabolic reactions are condensation r a *:ogf.73*grkvqh kgeactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways the rate of enzyme catalyz1ah v(v*m9 hbi u 1y)p-qrgcw4ed reactions can be measurmw ghy1rah-)v9(1pic q4*u vbed.
2.Draw a graph to show the effect of temperature on the reaction rate of an enzyme.


3.State how the optimum temperature can be determined using the graph drawn in part b.

1.Compare and contrast intracellular and extracellular chemical reactions, givena+9bur:d:c :( y 2evxvghcc)k one example of each type of reactkcr bd:a xyh:2ce):9uvv(+ c gion.
2.Enzymes are regulated by inhibitors that are classified as competitive or non-competitive. Distinguish between these two types of inhibitors.
3.Describe, using an example, how metabolic pathways can be regulated by end-product inhibition.